LOCATION LYONMAN CAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Vitrandic Argixerolls
TYPICAL PEDON: Lyonman gravelly ashy sandy loam--forestland. (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inch; very dark grayish brown (10YR 3/2) slightly decomposed organic matter consisting of needles and leaves very dark brown (10YR 2/2) moist; moderate thick platy structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine to medium interstitial pores; strongly water repellent, more than 60 seconds to adsorb a bead of water on the surface; 5 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary (.25 to 2 inches thick)
A1--1 to 7 inches; grayish brown (10YR 5/2) gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; moderate very fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; many very fine interstitial pores; 20 percent hard volcanic gravel; slightly acid (pH 6.4); clear wavy boundary. (3 to 8 inches thick).
A2--7 to 13 inches; grayish brown (10YR 5/2) very gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine through medium and common coarse roots; many very fine tubular pores; 1 percent stones, 5 percent cobbles, 50 percent hard volcanic gravel; neutral (pH 6.6); clear wavy boundary. (4 to 8 inches thick).
Bt1--13 to 18 inches; brown (10YR 5/3) very gravelly ashy loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; few fine, medium and coarse roots; many very fine interstitial pores; common distinct clay films on ped faces and lining pores; 1 percent stones, 2 percent cobbles and 50 percent hard volcanic gravel; neutral (pH 6.6); clear wavy boundary. (5 to 13 inches thick).
Bt2--18 to 31 inches; brown (7.5YR 5/4) extremely gravelly ashy loam, dark brown (7.5YR 3/4) moist; moderate medium subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; many very fine and few fine tubular pores; common distinct clay films on ped faces and lining pores; 1 percent stones, 2 percent cobbles and 60 percent hard volcanic gravel; neutral (pH 7.0); clear irregular boundary. (0 to 14 inches thick).
Crt--31 to 56 inches; very pale brown (10YR 8/2) soft weathered pyroclastic andesitic tuff, grayish brown (10YR 5/2) moist; pockets of clay weathered in place; few faint clay films along fractures.
TYPE LOCATION: Modoc County, California; on the Modoc National Forest in the Warner Mountains about 2.5 miles up the Deep Creek Road from Modoc County Road 1 about 1.5 miles south of Cedarville, CA.; no PLSS survey available; in projected section 3, T. 42 N., R. 15 E.; USGS Cedarville 7.5 minute topographic quadrangle; 41 degrees 30 minutes 51.3 seconds north latitude and 120 degrees 13 minutes 29.7 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - These soils are usually moist in winter, spring, and early summer, dry later in summer and fall; xeric soil moisture regime.
Mean annual soil temperature - 41 to 45 degrees F.
Mean summer soil temperature - 47 to 55 degrees F.
Oxalate Al + 1/2 oxalate Fe: 0.2 to 0.4 percent.
Volcanic glass content - 50 to 80 percent in the coarse silt through fine sand fractions.
Mollic epipedon thickness - 12 to 20 inches.
Depth to bedrock - 22 to 40 inches to a paralithic contact. The paralithic materials below the contact are weathered pyroclastic andesitic tuff.
Particle-size control section - Clay content: Averages 18 to 27 percent, (field estimates).
Rock fragments: 50 to 65 percent, mainly gravel or cobbles.
A horizons - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Rock fragments: Averages 35 to 70 percent, mainly gravel or cobbles.
Organic matter content: 1 to 4 percent.
Reaction - Moderately acid or slightly acid.
Bt horizon - Hue: 10YR or 7.5YR.
Texture: Ashy loam or ashy sandy clay loam.
Clay content: 18 to 27 percent.
Rock fragments: 50 to 65 percent.
Structure: Moderate or strong, fine to coarse subangular blocky.
Reaction - slightly acid or neutral.
COMPETING SERIES: These are the Chesebro (T, OR), Eep, Monasterio and Tourn series. Chesebro and Eep are very deep. Monasterio soils are moderately deep to a lithic contact and have a Btq horizon with silica pendants on undersides of rocks. Tourn soils have less than 35 percent rock fragments in the upper part of the profile. (The separation between the Tourn and Lyonman is not distinct, and further investigation is needed).
GEOGRAPHIC SETTING: Lyonman soils are on mountains. They formed in volcanic ash and colluvium over residuum derived from glassy tuff. Slopes are 15 to 50 percent. Elevations range from 5,300 to 7,500 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 20 to 25 inches, most of which comes as snow. The mean annual temperature is 38 to 44 degrees F. The frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Longval and competing Tourn soils. Longval soils are very deep and are cryic.
DRAINAGE AND PERMEABILITY: Well drained; medium or high surface runoff; moderate permeability.
USE AND VEGETATION: Lyonman soils are used for timber production, watershed, wildlife habitat, and limited livestock grazing. The vegetation consists of an open forest canopy of ponderosa pine and white fir with an understory of mountain big sagebrush, antelope bitterbrush, snowberry, mountain brome, Idaho fescue, slender wheatgrass, and bluegrass.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are not extensive with about 1,500 acres of the series mapped to date. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Modoc County (Alturas Area), California, 1974.
REMARKS: Previous authors and editor initials include: LNL, TDC, GMK.
The typical pedon relocated and redescribed. Field documentation and local glass counts support the change from fine-loamy, mixed superactive Xeric Argicryolls to ashy-skeletal, glassy, frigid Vitrandic Argixerolls.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - The zone from the mineral soil surface to 18 inches (A1, A2 and the Bt1 horizons).
Vitrandic intergrade feature -- High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 31 inches (A1, A2, Bt1, and the Bt2 horizons).
Argillic horizon - The zone from 13 to 31 inches (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 31 inches to underlying soft, weathered bedrock (Crt layer).
Particle-size control section - The zone from 13 to 31 inches (Bt1 and Bt2 horizons).